Polymers that consist of α-β-unsaturated carboxylic acids with polyoxyalkylene side chains, so-called polycarboxylates, have been used in concrete technology as dispersing agents, such as high-power liquefiers because of their strong water reduction. These polymers have a comb polymer structure. With the same water/cement (w/c) value, these polymers can improve processibility of the concrete, or, with the same processibility, reduce the water demand and thus the w/c value, which can lead to an increase in compressive strength and tightness.
The known polycarboxylates are only conditionally stable at elevated temperatures and decompose within days, such that they can no longer exert their action. It has been shown that the action of polycarboxylates greatly decreases when they are used at elevated temperatures in the presence of inorganic powders, such as hydraulic binders. This can occur, for example, in the storage of hydraulic binders or during milling of hydraulic binders.
During storage, in many cases the hydraulic binders are stored in silos at above 80° C., and even often at above 120° C. Moreover, high pressures can place special demands on the stabilization of polymers, and can be present in silos, such as in high silos. If polycarboxylates are added to the binder in advance, which can be in the desirable production of production mixtures, for example cement production mixtures, the mode of action of polycarboxylates greatly decreases after storage at high temperatures.
Polycarboxylates are also partially used as milling adjuvants during milling of hydraulic binders, for example clinker bricks. Since high temperatures are also present during milling, the known polycarboxylates can be decomposed to a large extent, and their action is no longer exerted.
Stabilizers are known that can be used for the stabilization of polymers, such as in polymer production or with use as adhesive. During polymer production or in adhesive, however, completely different conditions are present than when the polymers are used in the presence of inorganic powders. In the presence of inorganic powders, polycarboxylates are distributed over a large surface area. As a result, they are more fragile and are more quickly decomposed. In addition, this makes it difficult to stabilize polycarboxylates, such as at elevated temperatures.
It would therefore be desirable to develop a method for stabilization of polycarboxylates, so that polycarboxylates can be kept stable even in the case of a higher temperature in the presence of inorganic powders.